where, KPe  and KIe  denote the feedback gains。 Once it is

defined appropriately, the engine torque is also controlled indirectly by feedback of a speed tracking error。 Note that the desired engine speed  is  taken  as  the  maximum value of the prescribed engine speed and the idle  speed。  The block diagram of this scheme is shown in Fig。 6。 This approach easily provides an effective way for active damping of driveline oscillation。

V。 SIMULATION RESULTS

In this section, some simulation results are presented to illustrate the proposed gear shifting management strategy。 Fig。 7 shows the speed trajectory of the engine, clutch 1, and clutch 2 during 1-2 upshift case。 Speed synchronization between two clutches is performed from 1。0 to 1。5 sec。 As shown in Fig。 8, the engine torque is reduced right before the engagement of the second clutch in order to reduce shifting shocks。 Fig。 9 shows that oscillation of output shaft torque is reduced during the period after the second clutch is engaged。 According to Fig。 10, it is easily verified that the proposed method has the advantage presented in the control strategy。 The clutch normal force of the oncoming clutch is composed of feedback and feedforward control while that of the off- going clutch is derived by a feedforward control only。 At 1。1 sec, it can be observed that the off-going clutch torque is held while the oncoming clutch torque is commanded negative torque rate by the baseline feedback controller。 Thus, the proposed control method can prevent undesirable     actuator

effect like dead-zone nonlinearity。

VI。 CONCLUSIONS

In this paper, a novel control strategy for gear shifting of DCT vehicles is proposed to utilize the unique characteristics of dual clutch systems。 The resulting trajectories of the on- coming and the off-going clutch torques are formulated as  a

with a finite torque split。 In order to analyze and validate the proposed control scheme, simulations are performed for a vehicle model equipped with a  DCT。  The  results show that the proposed controller ensures good drivability of a vehicle in spite of fast gear shifting action。 In future works, robustness issues and several driving modes should be taken into account。

nondecreasing and a nonincreasing function, respectively。 As a result, the control inputs are made as convex   combination

REFERENCES

[1] J。 Fredriksson and B。 S。 Egardt, “Nonlinear control applied to gearshifting in automated manual transmission,” in Proc。 of the IJCEE, Conference on Decision and Control, Sydney, Austrailia, Dec。   2000。

[2] G。 Lucente, M。 Montanari, and C。 Rossi, “Modelling of an automated manual transmission system,” Mechatronics, vol。 17, pp。 73–91, 2007。

[3] J。 Horn, J。 Bambergera, P。 Michaub, and S。 Pindlb, “Flatness-based clutch control for automated manual transmissions,” Control Engineer- ing Practice, vol。 11, pp。 1353–1359,   2003。

[4] M。 Montanari, F。 Ronchi, C。 Rossi, A。 Tilli, and A。 Tonielli, “Control and performance evaluation of a clutch servo system with hydraulic actuation,” Control Eng。 Pract。, vol。 12, pp。 1369–1379,   2004。

[5] B。 Matthes, “Dual clutch transmissions - lessons learned and future potential,” SAE, Tech。 Rep。 2005-01-1021,  2005。

[6] M。 Kulkarni, T。 Shim, and Y。 Zhang, “Shift dynamics and control of dual-clutch transmissions,” Mechanism and Machine Theory, vol。 42, pp。 168–182, 2007。

[7] S。 J。 Park, W。 S。 Ryu, J。 G。 Song, H。 S。 Kim, and S。 H。 Hwang, “Development of dct vehicle performance simulator to evaluate shift force and torque interruption,” Int。 J。 Automot。 Technol。, vol。 7, no。 2, pp。 161–166, 2006。